1. Field of the Invention
This invention relates generally to a printer that is provided with a mounting unit for mounting a cartridge containing a recording medium, More specifically, it relates to a head release mechanism for printers of this form, capable of moving the print head, relative to the recording medium supplied from a mounted cartridge, to the print position and to a release position that is away from the print position.
2. Description of the Related Art
Printers referred to as tape printers and label printers have come into use in recent years. In general, the recording media used on this type of printer are tape-shaped media. The backside of such a recording medium is an adhesive surface covered by a piece of peel-off paper. The recording medium is stored in a cartridge in a spooled form. A cartridge-mounting unit for mounting the cartridge on a detachable basis is formed on the printer side. The cartridge-mounting unit is covered by a cover and is configured in such a way that one opens the cover to mount a cartridge, closes the cover, and then performs printing.
A head release mechanism is incorporated into the printer so that the print head that prints on the recording medium supplied from the mounted cartridge is not damaged when the cartridge is attached or detached and so that the print head does not hinder the cartridge attaching or detaching operation. The head release mechanism moves the print head from the print position, protruding to the recording medium side, to the release position, which is away from the print position.
FIG. 11A shows a conventional printer called a tape printer. As indicated in the figure, the first half of the top portion of printer 1 is keyboard 2. The second half is opening/closing cover 3. When cover 3 is opened, as illustrated in the figure, mounting unit 4 for tape cartridge 4 (see FIG. 11B ) formed inside the cover comes into view. Head unit 7, with a built-in thermal head 6 as a print head, is provided on mounting unit 5. As shown in FIG. 12, tape cartridge 4 holds, in its case 41, roll 8 for tape-form recording medium T and roll 9 for ink ribbon R. A transport path is formed so that these items become stacked at the position in which they pass through platen roll 42.
Formed adjacent to platen roll 42 is a head unit insertion hole 43 through which head unit 7 is inserted when a tape cartridge is mounted. Thermal head 6, which is incorporated in head unit 7 that is inserted into hole 43, can be moved by the head release mechanism built into the printer, from the print position (indicated by the solid line in the figure) protruding to the side of platen roll 42 to the release position (indicated by dashed lines in the figure) that is located in the back.
The conventional head release mechanism basically comprises a head carrier component that supports thermal head 6 to allow the thermal head to move from the print position to the release position, a spring component that always holds the component onto the side of the head release position, a moving component that moves the head carrier component to the print position against the spring force of the spring component, and a locking component that locks the head carrier component, that has moved to the print position, in the new position. The head release mechanism of this composition is incorporated into the backside of the cartridge-mounting unit.
In printer 1 shown in FIG. 11A, the moving component that moves thermal head 6 to the print position is protrusion 31 that is formed on the backside of cover 3. When cover 3 is closed, protrusion 31 intrudes into hole 11, formed on the case side, and moves the internally provided head carrier component toward the print position against the spring force. Therefore, when cover 3 is closed, against the spring force, the head carrier component is moved by protrusion 31 in conjunction with the closing operation. This causes head 6, held at that location, to protrude into the print position. When cover 3 is completely closed, hook 32, formed on the front edge of cover 3, is inserted into hole 12, that is formed on the case side. The hook couples with the hook engagement unit formed in the interior of the hole. This causes the cover to be locked in the closed condition. Thus, the head carrier component is locked into the print position.
To open cover 3, one operates cover-opening button 13. Operating button 13 releases the lock and opens cover 3. As a result, the head carrier component released from protrusion 31 of cover 3 is returned to the release position by the spring force. Therefore, thermal head 6 is retracted to the release position inside head unit 7. In this manner, opening cover 3 automatically creates a condition in which the head is released, thus permitting tape cartridge replacement and similar operations.
In the head release mechanism of this form, protrusion 31 formed integrally on cover 3, presses head 6 onto the print position, and hook 32, formed integrally on cover 3 maintains the print state. Therefore, the pressing force that presses the head onto the print position always acts on cover 3. Further, since the head load acts directly on cover 3, the head load is controlled by cover 3.
On the other hand, head release mechanisms that are not tied to the opening and closing actions of cover 3 are in the public domain. For example, as shown in FIG. 13, a release lever 14 is placed at a position that becomes exposed when cover 3 is opened. This release lever 14 is movable from a position over tape cartridge 4, that is mounted and centered at one end of the release lever, to a position away from that position. By moving lever 14 to a position above tape cartridge 4, one can move head 6 to the print position. By moving the head from that position to the position indicated by the solid line in the figure, one can retract head 6 to the release position.
In a head release mechanism in which the opening and closing actions of cover 3 are separate from the head release operation, the tape cartridge could be replaced inadvertently even when the head is not released (i.e., when the head is still at the print position). However, if the head is at the print position, lever 14 is at a position that hinders the tape cartridge replacement operation. This prevents the occurrence of the problem mentioned above. The use of this mechanism, however, always requires a lever operation for releasing the head or for setting the head in the print position, in addition to the operation of opening and closing cover 3.
The conventional head release mechanism described above contains the following problems that must be addressed:
First, in a form in which a head release mechanism is constructed using a cover, a protrusion formed on the cover itself presses the head onto the print position. Therefore, the pressing force directly acts on the cover. Since load is always acting on the cover, the cover itself is liable to deform. When a deformation occurs, the head load changes with the result that the head release mechanism can potentially lose its ability to correctly position the head in the print position.
On the other hand, in the form in which the cover and the head release mechanism are completely separate, the release lever must be operated in order to release the head and press it onto the print position as separate from the operation of opening and closing the cover. While it facilitates controlling the head load or the head position, this requires a lever operation each time the tape cartridge is attached or detached, thus adding to operational complexity.